A color filter method and a field sequential method are known as display methods for liquid crystal display devices. In a liquid crystal display device in which images are displayed by a color filter method, a plurality of subpixels each having a color filter that transmits only light with a wavelength of a given color (e.g., red (R), green (G), or blue (B)) are provided in each pixel. A desired color is produced in such a manner that transmission of white light is controlled in each subpixel and a plurality of colors are mixed in each pixel. On the other hand, in a liquid crystal display device in which images are displayed by a field sequential method, a plurality of light sources that emit lights of different colors (e.g., red (R), green (G), and blue (B)) are provided. A desired color is produced in such a manner that the plurality of light sources sequentially emit light and transmission of light of each color is controlled in each pixel. In other words, a desired color is produced by dividing the area of one pixel between lights of given colors in a color filter method, whereas a desired color is produced by dividing a display period between lights of given colors in a field sequential method.
The field-sequential liquid crystal display device has the following advantages over the color-filter liquid crystal display device. First, in the field-sequential liquid crystal display device, it is not necessary to provide subpixels in a pixel. Thus, the aperture ratio or the number of pixels can be increased. In addition, in the field-sequential liquid crystal display device, it is not necessary to provide a color filter. That is, loss of light due to light absorption in the color filter does not occur. For that reason, the transmittance can be increased and power consumption can be reduced.
Patent Document 1 discloses a field-sequential liquid crystal display device. Specifically, Patent Document 1 discloses a liquid crystal display device that includes pixels each including a transistor for controlling input of an image signal, a signal storage capacitor for holding the image signal, and a transistor for controlling transfer of electric charge from the signal storage capacitor to a display pixel capacitor. In the liquid crystal display device having this structure, writing of an image signal to the signal storage capacitor and display corresponding to electric charge held at the display pixel capacitor can be performed concurrently.